Ok I tested the breather valve, 45.6 ohm so coil is good. A little confused you said "should be closed without power" Without power I can blow in the direction of the arrow only. Should the valve be completely closed in either direction?
Originally Posted by shogun
We had that 2 times on an E32 750 Alpina B12.
First time the ground cable from the engine to chassis was bad. That we replaced and idle was stable.
Second time the return line from fuel tank = fuel tank breather line and the valve were defective/broken. See here on the B12 http://e32b12.blogspot.jp/ click in the index on idle and scroll far down.
That is the system on a M30 http://www.realoem.com/bmw/enUS/show...diagId=16_0112
17 Fuel tank breather valve BOSCH 13901711395
The tank breather valve should have a resistance of 45 ± 20 Ohm and should be closed without power.